1. Field of the Invention
The present invention relates to a vehicular object detection system mounted in a vehicle that detects an object in front of the vehicle, and a tracking control system employing the vehicular object detection system.
The present invention also relates to a vehicle control system that includes an object detection system for detecting an object in front of a subject vehicle, a locus estimation system for estimating a travel locus of the subject vehicle, and a control object determination system for determining a control object with respect to which the travel of the subject vehicle is controlled, based on outputs from the object detection system and the locus estimation system and on predetermined control object determination.
2. Description of Related Art
Japanese Patent Application Laid-open No. 5-174296 discloses an inter-vehicle distance detection and warning system in which the distance between a subject vehicle and a preceding vehicle is detected by a radar device and a warning is issued to a driver when the inter-vehicle distance becomes a predetermined value or less, to thereby prevent collision. A detection area of the radar device is changed according to change in the speed of the subject vehicle.
In the above-mentioned conventional arrangement, the detection area of the radar device is changed according to the vehicle speed. But, even when the vehicle speed is constant, the possibility of collision differs between a case where the driver has noticed the inter-vehicle distance decreasing and has the intention of decelerating and a case where the driver has no intention of decelerating. Therefore, it is not always appropriate to change the detection area according to the vehicle speed alone without taking into consideration the driver's intention.
Further, the detection area is generally set to be along the travel locus of the subject vehicle and substantially as wide as a lane so that the radar device detects a preceding vehicle. However, when there is an intersection, etc. in front of the vehicle, the driver must also pay attention to any vehicles cutting in from the side into the travel locus of the subject vehicle. Therefore, in detection of a preceding vehicle based on a narrow detection area substantially having the lane width, there might be a gap between the detection and the driver's consciousness. Widening of the detection area is undesirable in solving this problem, because a vehicle in the opposite lane might be erroneously detected, or the data processing load of the object detection system might increase.
As shown in FIG. 2A and FIG. 2B, when a vehicle cuts in between the subject vehicle and the preceding vehicle at an intersection, the driver generally drives the subject vehicle while paying attention not only to the preceding vehicle but also to the vehicle that cuts in. That is, if the driver recognizes in advance that a vehicle will cut in, the driver assumes that this vehicle will cut in between the subject vehicle and the preceding vehicle, and eases up on the accelerator pedal or prepares to press on the brake pedal in order to avoid moving closer to the preceding vehicle.
On the other hand, when constant inter-vehicle distance control is carried out, in which the distance between a subject vehicle and a preceding vehicle is maintained to be constant, the detection area of the radar device is set to be relatively narrow as shown in FIG. 2A. The radar device detects the preceding vehicle but often does not detect a vehicle that is cutting in. In such a case, the radar device does not detect the cutting-in vehicle although the driver is aware of the cutting-in vehicle, and therefore the constant inter-vehicle distance control is continued without taking into consideration the cutting-in vehicle. This can cause the driver to feel uncomfortable.
Alternatively, if the detection area of the radar device is unnecessarily increased as shown in FIG. 2B, a cutting-in vehicle that will not interfere with travel of the subject vehicle is detected as a control object. This causes sudden automatic braking to be executed during constant inter-vehicle distance control, which may again cause the driver to feel uncomfortable.